The present invention relates to a stencil printer and more particularly to a stencil printer of the type including a multistage paper feeding device capable of feeding papers of different kinds and an ink drum shiftable in the widthwise direction of the papers perpendicular to a direction in which the papers are conveyed.
A digital stencil printer is conventional which uses a laminate thermosensitive stencil made up of a thermoplastic resin film and a porous support adhered to each other. The printer includes a thermal head for selectively perforating, or cutting, the resin film of the stencil with heat in accordance image data. After the perforated stencil or master has been wrapped around an ink drum, ink feeding means arranged in the drum feeds an adequate amount of ink to the inner periphery of the drum. A press roller, press drum or similar pressing member presses a paper or similar recording medium against the ink drum so as to transfer the ink from the drum to the paper via the porous portion of the drum and the perforations of the master. As a result, an image represented by the image data is printed on the paper. Usually, a paper feeding device for continuously feeding papers one by one is built in the printer. The paper feeding device generally includes a feed tray to be loaded with a stack of papers and a pair of side fences for guiding the papers in the widthwise direction of the papers.
With the above printer, it is possible to shift the position of an image on the paper in the widthwise direction of the paper perpendicular to the direction of paper conveyance by shifting the feed tray of the paper feeding device in the widthwise direction. However, the adjustment of the shift relying on eyesight and the manual shift of the feed tray cannot easily implement delicate adjustment or accurate adjustment. In light of this, Japanese Patent Laid-Open Publication No. 5-306025, for example, discloses an arrangement for automatically shifting the feed tray of the paper feeding device.
To meet various kinds of needs, a stencil printer including a multistage paper feeding has recently been proposed. The multistage paper feeding device has a plurality of paper stocking portions and is capable of feeding papers of particular kind from each paper stocking portion. For such a multistage paper feeding device, Japanese Patent Laid-Open Publication No. 6-345281, for example, teaches an arrangement for automatically shifting a plurality of feed trays in the widthwise direction of the papers at the same time.
However, in any one of the conventional arrangements, a paper discharge tray for receiving papers, or printings, is not shiftable although the feed tray is shiftable. This brings about a problem that when the feed tray is shifted, the resulting printings cannot be accurately positioned on the discharge tray, and a problem that a pair of side fences on the discharge tray must be shifted independently of each other, obstructing easy operation. The arrangement taught in the above Laid-Open Publication No. 6-345281 has a drawback that a complicated construction is necessary for all of the feed trays to be shifted at the same time. Moreover, when the center of any one of the feed trays is deviated, the position of an image on a paper varies and must be adjusted every time the feed tray is selected.
To solve the above problems, Japanese Patent Laid-Open Publication No. 9-104159, for example, proposes an arrangement including a fixed feed tray and a fixed paper discharge tray and an ink drum shiftable in the widthwise direction of a paper and thereby allowing the position of an image to be adjusted. However, a stencil printer including both of an ink drum shiftable in the widthwise direction of a paper and a multistage paper feeding device has not been reported yet.
Today, a stencil printer is often operated with a large capacity paper feeding device, sorter, large capacity paper discharging device or similar peripheral unit connected thereto for meeting the demand for a great number of and various kinds of printings. Conventional peripheral units, however, lack an arrangement for shifting printings in the widthwise direction thereof, and each include a paper transport path arranged in a particular position. In practice, therefore, it is difficult to adjust the position of an image in the widthwise direction of a paper with the combination of a stencil printer and a peripheral unit.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 5-124734, 9-202032, 10-1254, 8-259008 and 6-293175 and U.S. patent application Ser. Nos. 08/796,696 (pending) and Ser. No. 09/151,351 (pending).
It is therefore an object of the present invention to provide a stencil printer capable of adjusting, with a simple construction, the position of an image to be printed on a paper fed from any one of a plurality of paper stocking portions in the widthwise direction of the paper, and allowing a desired peripheral unit to be operatively connected thereto.
A stencil printer of the present invention includes a multistage paper feeding device having a plurality of paper stocking portions and capable of selectively feeding a plurality of different kinds of papers. An ink drum is shiftable in a direction perpendicular to a direction of paper conveyance and allows a master formed with an image to be wrapped therearound. A paper discharge tray stacks the papers each carrying a printed image thereon. The paper stocking portions each include at least a pair of side fences for positioning the papers in the widthwise direction of the paper. The paper discharge tray includes at least a pair of side fences for positioning the papers carrying printed images thereon in the widthwise direction of the paper. The paper stocking portions and paper discharge tray are arranged in the printer with center lines thereof coinciding with the center line of the paper transport path. The side fences of the paper discharge tray are interlocked to each other and movable in the widthwise direction of the paper symmetrically to each other with respect to the center line of the paper transport path.